Ink refill cartridge for writing instrument



FIG. 1 is a top, left, rear perspective view of an ink refill cartridge for writing instrument showing my new design;

FIG. 2 is a left side elevational view thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a rear elevational view thereof;

FIG. 7 is a front elevational view thereof; and,

FIG. 8 is a bottom, left, rear perspective view of thereof. 

CLAIM I claim an ornamental design for an ink refill cartridge for writing instrument, as shown and described. 